Study of charmonium production in b -hadron decays and first evidence for the decay Bs0

Abstract

Using decays to φ -meson pairs, the inclusive production of charmonium states in {b} -hadron decays is studied with pp collision data corresponding to an integrated luminosity of 3.0 { fb}^{-1} , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. Denoting by B_C ≡ B (b → CX) × B (C→ φφ) the inclusive branching fraction of a {{b}} hadron to a charmonium state C that decays into a pair of φ mesons, ratios R^{C_1}_{C_2}≡ B_{C_1} / B_{C_2} are determined as R^{χ_{c} 0}_{{η _{{c}}} (1S)} = 0.147 ± 0.023 ± 0.011, R^{χ_{c} 1}_{{η _{{c}}} (1S)} = 0.073 ± 0.016 ± 0.006, R^{χ_{c} 2}_{η _{c} (1S)} = 0.081 ± 0.013 ± 0.005, R^{χ_{c} 1}_{χ_{c} 0} = 0.50 ± 0.11 ± 0.01, R^{χ_{c} 2}_{χ_{c} 0} = 0.56 ± 0.10 ± 0.01 and R^{{η _{{c}}} (2S)}_{{η _{{c}}} (1S)} = 0.040 ± 0.011 ± 0.004. Here and below the first uncertainties are statistical and the second systematic. Upper limits at 90% confidence level for the inclusive production of X(3872), X(3915) and χ_{c} 2} (2P) states are obtained as R^{X(3872)}_{χ_{c} 1} < 0.34, R^{X(3915)}_{χ_{c} 0} < 0.12 and R^{χ_{c} 2} (2P)}_{χ_{c} 2} < 0.16. Differential cross-sections as a function of transverse momentum are measured for the {η _{{c}}} (1S) and χ _c states. The branching fraction of the decay B ^0_{s} → φ φ φ is measured for the first time, B ( B^0_{s} → φφφ) = (2.15 ± 0.54 ± 0.28 ± 0.21_{B}) × 10^{-6}. Here the third uncertainty is due to the branching fraction of the decay B^0_{s} → φ φ , which is used for normalization. No evidence for intermediate resonances is seen. A preferentially transverse φ polarization is observed. The measurements allow the determination of the ratio of the branching fractions for the {η _{{c}}} (1S) decays to φ φ and p {\overline{p}} as B( η_{c} (1S)→ φφ)/B(η_{c} (1S)→ p {\overline{p}} ) = 1.79 ± 0.14± 0.32.